Sudden cardiac arrest (colloquially “heart attack”) is a regular killer. The best treatment for cardiac arrest is quick and competent chest compressions to keep blood flowing through a victim's heart. Generally, every minute of delay in treating a cardiac arrest victim lowers the chance of survival by about ten percent. As a result, the ability to provide CPR in a competent manner can be a very important personal skill, and is particularly important for professional healthcare workers such as emergency medical technicians (EMTs).
Various CPR feedback devices are available that indicate to a rescuer whether they are performing CPR chest compressions at an appropriate rate and an appropriate depth of compression, such as dictated by American Heart Association (AHA) guidelines. For example, the PocketCPR application for iPhones and iPods may be used for practicing CPR, such as on a dummy or foam block, and may indicate whether a recent series of compressions was performed at the proper rate and proper depth. Similarly, the ZOLL Medical CPR D-Padz are defibrillation pads that connect to a defibrillator and include an accelerometer that can be used to compute the depth and rate of chest compressions on the victim so that the defibrillator can indicate via recorded voice prompts that a rescuer should be instructed, for example, to “press harder” if the unit determines that the depth of compression is too shallow.
Professional responders such as EMTs may also receive after-the-fact feedback via processes sometimes referred to as code reviews. In particular, data from a patient monitor (which may be incorporated into a defibrillator) may be saved and may then be loaded into a computer where the responder and a supervisor may review the data and then may discuss where the responder made errors or performed well, and what the responder can do to improve his or her performance. Sometimes these code reviews may occur well after the event, after the responder has largely forgotten the key aspects of the event.